1. Field of the Invention
The present invention relates to a solar cell module, a building material with a solar cell module, a solar cell module framing structure, and a solar power generation apparatus.
2. Related Background Art
In recent years, solar cell modules have been very popular. Demand has greatly arisen for solar cell modules for a middle-scale power system installed outdoors in personal residences.
To generally use solar cell modules for a power system, a plurality of modules are connected in series to obtain a series unit for generating a predetermined voltage or more. The series units are connected in parallel to form a solar cell array.
An example of a circuit diagram of a solar cell module 2401 will be described in FIG. 24A. The solar cell module 2401 has a solar cell element A1 and a bypass diode A2 connected in parallel to the solar cell element A1. When the solar cell module 2401 is partially shadowed, the solar cell element A1 is set in a high-resistance state, and the following phenomenon called xe2x80x9cpartial shadowxe2x80x9d occurs. That is, a voltage generated by the solar cell modules in other series units is applied as a reverse bias voltage to the solar cell module via a load. The bypass diode A2 drains the reverse bias voltage applied to the solar cell element A1 in the solar cell module to prevent damage to the solar cell element A1.
When some solar cell modules of the solar cell array made up of a plurality of solar cell models malfunction to cause an abnormal array output, the malfunctioning portions are detected as follows. It is checked if an electrical output from each series unit is normal. The solar power generation apparatus is then stopped. The electrical outputs from the respective solar cell modules constituting the series units are measured using output terminals of the solar cell modules which are located on the nonexposed surfaces of the solar cell modules.
Since these output terminals are often located on the lower surfaces of the solar cell modules, it is very difficult to measure the electrical outputs from the solar cell modules upon installation. A detection terminal may be arranged for each solar cell module. However, when the detection terminal is exposed outside, short circuiting or power shock may occur, thus suffering a problem on reliability. In general, no detection terminal is arranged for each solar cell module.
To specify the malfunction in the solar cell array, a method of measuring a current flowing in the wiring of the solar cell array using a clamp type ammeter is generally practiced.
Conventional solar cell modules each having a current detection unit not exposed outside are disclosed in Japanese Patent Application Laid-open No. 6-125105 in FIGS. 24B-1 and 24B-2 and Japanese Patent Application Laid-open No. 9-148613 in FIG. 24C).
Referring to FIGS. 24B-1 and 24B-2, solar cell modules 2401 have magnetic field generation unit B1 and B2, respectively. Referring to FIG. 24C, a solar cell module 2401 has a light-emitting unit C1. As shown in FIG. 24B-1, when an operating current of the solar cell flows in the magnetic field generation unit B2, a magnetic field is generated. As shown in FIG. 24B-1, when a current flows into a bypass diode A2, the magnetic field generation unit B1 generates a magnetic field. As shown in FIG. 24C, the light-emitting unit C1 is turned on when a current flows into a bypass diode A2. The ON/OFF operation of the light-emitting unit can be visually checked. The magnetic field generated by the magnetic field generation unit can be checked by a magnetic needle or a lead switch sensing a magnetic field.
The arrangement shown in FIG. 24B-2 detects the malfunction using generation of a current (I1: operating current) during operation of the solar cell element A1. The arrangement shown in FIG. 24B-1 detects the malfunction when a reverse bias voltage is generated by the same principle of partial shadow in the solar cell module when the voltage of the solar cell element A1 lowers due to the malfunction to flow a current (I2: current flowing upon malfunction of the solar cell module) through the bypass diode A2.
These methods of specifying the malfunctions of the solar cell modules suffer the following problems.
(1) When the solar cell array malfunctions, the operator must go up to the installation surface of the solar cell modules and check the solar cell modules on the installation surface one by one. The job is cumbersome, and the xe2x80x9cpartial shadowxe2x80x9d occurs due to the shadow of the operator himself on the solar cell modules. It is difficult to specify a malfunctioning solar cell module.
(2) A given sunbeam is required to specify a malfunctioning solar cell module. For example, to specify the malfunction of a solar cell in a cloudy day, the magnetic field generation unit and light-emitting unit cannot properly operate. It is, therefore, difficult to specify a malfunctioning solar cell module.
(3) Since the conventional malfunction detection method is based on a single parameter such as an operating current of the solar cell element or current flowing through the bypass diode, these methods cannot cope with a variety of malfunction modes of solar cell elements and a solar cell array arrangement.
The present invention has been made in consideration of the conventional problems described above, and has as its object to provide a solar cell module capable of easily detecting or specifying a malfunctioning solar cell module by providing the following unit, and a building material with the solar cell module, a solar cell module framing structure, and a solar power generation apparatus.
The present invention has been made in consideration of the above problems.
More specifically, it is an object of the present invention to more easily and accurately specify the malfunction of a solar cell module. It is another object is to easily specify a malfunctioning solar cell module.
It is still another object of the present invention to provide a solar cell module comprising at least one solar cell element, at least one electrical parameter detection unit for the solar cell element, and communication unit for performing communication in accordance with an output from the electrical parameter detection unit. It is still another object to provide a solar cell module building material having this solar cell module.
It is still another object of the present invention to provide a solar cell module framing structure having the solar cell module, a nonsolar cell member, and display unit responding to a signal from the communication unit, wherein the display unit is arranged on the nonsolar cell member.
The communication unit preferably has signal generation unit and more preferably has superposing unit.
It is still another object of the present invention to provide a solar power generation apparatus having a plurality of solar cell modules and signal generation unit arranged for the plurality of solar cell modules. Preferably this solar power generation apparatus has the display unit and is installed in a power-related device.
Preferably, the solar power generation apparatus comprises superposing unit and signal separation unit.
Since the communication unit is arranged in the solar cell module, the operator need not check whether the malfunction occurs near the solar cell module. The shadow of the operator himself is not formed on the solar cell module. This allows the operator to accurately specify the malfunction.
Since the display unit which receives a signal from the communication unit is centralized in the nonsolar cell member forming the solar cell module framing structure, the cost of the display member can be reduced. Since the display unit can be located at an unnoticeable position, the degree of freedom in design of the solar cell array can increase.
The display unit for receiving a signal from the communication unit can be incorporated in the power-related device such as an inverter. With this arrangement, the operator need not go up to the installation surface to specify a malfunctioning solar cell module, thus improving maintainability. In this arrangement, a display device conventionally used in a power control device can serve as this display unit. In addition, when recording unit is used together with this display unit, the electrical parameter of each solar cell module in a fine day is recorded in advance, and the malfunctioning solar cell module can be specified based on the electrical parameter. The malfunctioning solar cell module can be specified even in a cloudy day and can be replaced with a new one in the cloudy day.
External communication unit may be used to make a control device of a power company or subcontractor cooperate with a computer in the power-related device via a telephone line. More accurate malfunction detection and regional operation of the solar power generation apparatus are allowed on the basis of a larger quantity of parameter information than that in conventional malfunction detection, and changes over time of the parameter information.
The signal generation unit for generating a specific signal (ID information) is arranged in units of solar cell modules. The malfunctioning solar cell module can be specified due to the presence/absence of this signal or the difference between such signals.
The signal generated by the signal generation unit is superposed on the electrical output from the solar cell module. The electrical output cable of the solar cell module is used as the path of the signal from the signal generation unit. The signal from the signal generation unit can be easily supplied to the power-related device such as an inverter. A dedicated wiring for feeding such a signal need not be arranged, thus facilitating installation and maintenance. The material cost of the dedicated wiring can be reduced.
As described above, according to the present invention, a malfunctioning solar cell module can be easily specified, thus improving maintainability.